1. Field of the Invention
The present invention relates generally to apparatus for measuring the temperature of a polymer melt and more particularly to such apparatus employing a conical member having a thermocouple at its apex end immersed in the melt.
2. Description of the Prior Art
The manufacture of thermoplastic articles and particularly tubular products such as pipes and tubes by extruding a polymer melt is generally well known in the prior art. In these processes, the polymer melt is fed from a melt chamber to an annular die comprising basically an outer annular body surrounding an inner mandrel. The melt flows through an annular passageway formed between the annular body and the mandrel and exits through an extrusion orifice where the tube or pipe is formed.
It is important in these extrusion processes to maintain the temperature of the melt within certain desirable limits in order to assure that the melt remains consistent during its travel from the melt chamber to the die. In order to accomplish this goal, it has been the practice to immerse a thermocouple directly into the melt for measuring its temperature. Although this practice has proven satisfactory, it has nonetheless created other serious problems. One problem is that the immersion of the thermocouple in the melt disturbs the melt flow and can produce turbulence causing degradation of the melt. This degradation can lead in many cases to serious defects in the extruded product.